On November 6, 2009, the U.S. Environmental Protection Agency (EPA) proposed significant new use rules (SNUR) under Section 5(a)(2) of the Toxic Substances Control Act (TSCA) for two chemical substances that were the subject of premanufacture notices (PMN). EPA identified the substances generically as multi-walled carbon nanotubes and single-walled carbon nanotubes. According to the notice, these substances are subject to TSCA Section 5(e) consent orders issued by EPA. The consent orders require protective measures to limit exposures or otherwise mitigate the potential unreasonable risk. The proposed SNURs are based on and consistent with the provisions in the underlying consent orders, and designate as a significant new use the absence of the protective measures required in the corresponding consent orders. Persons who intend to manufacture, import, or process either of these two substances for an activity that is designated as a significant new use would be required by the proposed rule to notify EPA at least 90 days before commencing that activity. The required notification would provide EPA with the opportunity to evaluate the intended use and, if necessary, to prohibit or limit that activity before it occurs. Comments are due December 7, 2009.